modify environments to make sandboxes

[Mildred]

Hi,

I'm new to this mailing list and also new to the scheme language ...
I'm used to Lua but I try to search about functionnal programming, and
I found scheme. It looks like a good language but before using it in my
projects I would like to know if tere is an easy way to create
sandboxes.

In lua, it is easy, you create a table containing functions ... and the
table can be made environment for a function. So, you can easily create
secure sandboxes by loading lua code from file and changing the
environment of the loaded code.

I do not know how to do that in scheme. Apparetly the function
null-environment can return an environment and eval can evaluate some
code in an environment. But the question is how to define a variable in
an environment and also how to undefine a variable that you don't want
to appear.
I didn't found anything about modifying an environment. Is it
possible ? If not, why not ? and is it possible to create sandboxes ?
Thanks

Mildred

-- 
Mildred       <xmpp:address@hidden> <http://mildred632.free.fr/>
Clef GPG :    <hkp://pgp.mit.edu> ou <http://mildred632.free.fr/gpg_key>
Fingerprint : 197C A7E6 645B 4299 6D37 684B 6F9D A8D6 [9A7D 2E2B]